1. Field of the Invention
The invention relates to means to improve the pop-up type dispensing of sheets arranged in an interleaved stack, and more particularly to means to shape the stack to minimize dispensing failure.
2. Description of the Prior Art
The teachings of the present invention are directed to a pop-up type dispensing package for a stack of discrete, interleaved sheets. The present invention is particularly applicable in instances where the sheets themselves are characterized by a stiffness which may be defined for purposes of this disclosure and the claims that follows as being such that, when the sheets are arranged in a conventional interleaved stack wherein the interleaved sheet portions are substantially planar and horizontal, during the removal of a given sheet from the stack through the package dispensing orifice the portion of the next succeeding sheet overlying a portion of the sheet being removed tends near its adjacent folded edge to lift away from the sheet being removed, permitting the sheet being removed to slip out from under the succeeding sheet. This results in failure of the succeeding sheet to achieve its pop-up position through the dispensing orifice.
Sheets demostrating such stiffness are well known in the art and the material from which such sheets are made does not constitute a limitation on the present invention. For example, sheets demonstrating such stiffness may be made of paper, film, woven or nonwoven natural or synthetic fibers, or the like. The stiffness characteristics of the sheet may result from its composition, the fibers used, the binder used, materials with which the sheet is pretreated or the like, all as is well known in the art.
Sheets demonstrating stiffness of the type described above are frequently chosen for various ones of their properties such as strength, resistance to tearing and the like. In recent years there has been increased interest in sheets, towelettes or the like pre-moistened with a volatile component. The composition and purpose of the volatile component may vary widely. Non-limiting examples of such volatile components may include perfume, cleaning compound, wax, insecticide or insect repellent, topical medicaments and cosmetics. Generally, such pre-moistened sheets demonstrate the sort of stiffness contemplated by the present invention by virtue of their composition so that they are compatible with the solvent of the volatile component, because of their strength and durability so that they may be used as wipes or the like and because of their pleasing appearance and tactile properties.
Pre-moistened sheets have been packaged in numerous ways. For example, U.S. Pat. No. 3,499,575 in the name of Winston G. Rockefeller, issued Mar. 10, 1970 teaches a container for pre-moistened sheets having a reclosable lid to prevent evaporation of the volatile component with which the sheets are pre-moistened. The sheets are arranged in the container in a non-interleaved stack and a support member is provided in the container for the stack to raise the central portion of the stack to facilitate withdrawal of the individual sheets from the container. Pre-moistened sheets have also been arranged in a conventional, interleaved, flat stack in a container having a dispensing orifice providing pop-up dispensing of the individual sheets. In such instances, however, should be given sheet be withdrawn from the stack by the consumer and the next succeeding sheet fail to achieve its pop-up position in the container orifice, the orifice is usually so sized that the next succeeding sheet can be restarted by the consumer with his fingers. An example of this type of package is taught in U.S. Pat. No. 3,780,908 in the name of William E. Fitzpatrick, Leonard Berger and Hayward B. Auerbach, issued Dec. 25, 1973.
While it will be understood by one skilled in the art that the teachings of the present invention are not intended to be restricted to a pop-up type dispensing package for a stack of interleaved, pre-moistened sheets (the invention being equally applicable to such a package containing interleaved dry sheets demonstrating the above mentioned tendency to lift by virtue of their stiffness), the invention will be described for purposes of an exemplary showing in its application to a package of the type taught in the commonly owned copending application Ser. No. 711,929, filed Aug. 5, 1976, in the name of Robert F. McCarthy and entitled PACKAGE FOR DISCRETE PRE-MOISTENED INTERLEAVED SHEETS AND THE POP-UP DISPENSING THEREOF.
Briefly, the above mentioned copending application teaches a moisture-proof package of discrete, interleaved, pre-moistened product sheets. The package comprises a tray-like portion to receive the sheet stack and a cover usually sealed to the tray-like portion. The cover is provided with a dispensing opening so dimensioned as to enable twice the cross sectional area of a pre-moistened sheet (i.e. two pre-moistened sheets in tightly gathered form) to pass therethrough without such undue friction as would cause the sheets to jam, tear or separate before the next succeeding sheet is presented for subsequent removal. The succeeding sheet not only is presented for subsequent removal, but also serves in the meantime as a plug for the dispensing opening, minimizing evaporation of the volatile composition with which the sheets have been pre-moistened. No additional closure or lid is required to be closed by the consumer to prevent dry-out.
The package of the above mentioned copending application serves as an excellent example of a package to which the teachings of the present invention may be applied not only because the sheets contemplated for use therewith would normally demonstrate the sort of stiffness described above, but also because the restricted dispensing opening is too small for the operator to conveniently reach therethrough to restart a succeeding sheet, should the succeeding sheet fail to achieve its pop-up position through the dispensing orifice. Reliability of the pop-up type dispensing of this exemplary package is of considerable importance because it is preferred that the cover be permanently or semi-permanently sealed to the tray-like portion of the package.
The present invention is based upon the discovery that if means are provided to support and so configure the stack as to cause the central portion of the stack to be depressed so that the interleaved portions of the sheets are non-planar and are concave in at least one plane in which the vertical axis of the package lies, failure of the pop-up type dispensing of the sheets will be greatly minimized or eliminated.